This invention relates to wireless switching and, in particular, to routing of calls within a wireless switching system.
A problem with the use of in-building or campus personal communication systems (PCS) is the limited capacity of the base stations to communicate active calls. Often in the prior art, the base stations are only capable of having two to four active calls at any time. However, a base station in such modern protocols as PHS, DECT, or PWT protocols can have more wireless handsets registered than the base station has the capacity to handle active calls. Unfortunately, one drawback with this approach is how to handle the case where a base station is at its active call capacity and a new call arrives for a handset currently registered on the base station. Some vendors attempt to overcome this problem by employing an algorithm in the handset to recognize when its serving base station is at capacity and then re-register to a new base station after a period of time. However, this causes two additional problems. First, while the handset is determining its condition and waiting, new calls to it cannot be delivered. Second, for some areas where a base station could have a large number of registered handsets, the algorithm will cause a large number of re-registrations from the base station. Further, when the call capacity of the base station becomes less than the maximum, a large number of registrations for wireless handsets returning to the base station also occur. Both of these problems have a de-stabilizing effect on a wireless switching system. Further, the problem, that doing frequent re-registrations present for a handset, is that the handset expends a great deal of power from its battery for each registration operation that it performs. This limits the time before the battery of a wireless handset must be recharged.
The foregoing problems are solved, and a technical advance is achieved, by an apparatus and method that results in a wireless handset not performing a re-registration operation when its serving base station is at capacity and allowing a wireless controller controlling a wireless switching system to send incoming calls for the wireless handset to the base station even if the base station is at capacity. The base station signals a new call to the wireless even if the base station is at its active call capacity. The wireless handset is responsive to the incoming call to perform a base station re-direct operation to a new base station that has idle call capacity and the call setup is completed to the wireless handset via the new base station. Advantageously, the base station re-direct operation is a new wireless operation for implementing the invention. advantageously, the base station re-direct operation is controlled by the system wireless controller in a second embodiment of the invention.
Other and further aspects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawing.